This invention relates generally to improvements in automatic pool cleaners and related accessories therefor, wherein the pool cleaner is designed for travel within a swimming pool or the like to dislodge and collect debris. More specifically, this invention relates to an improved filter bag for removable mounting onto the pool cleaner for collecting debris, wherein the filter bag is designed for convenient and economical disposal following a single use cycle, as shown and described in copending U.S. Ser. No. 10/917,790. The improved filter bag further defines a bag interior subdivided by a divider seam into a primary flow chamber for receiving flow of water and water-entrained debris from the pool cleaner, and a secondary collection chamber for trapping and collecting the water-entrained debris, wherein this divider seam is defined by a spaced-apart array of welds to form a divider seam of increased strength and resultant increased tear resistance.
Automatic swimming pool cleaners are well known in the art for use in maintaining a swimming pool in an overall state of cleanliness. In this regard, residential and commercial swimming pools normally include a standard waterfiltration system including a main circulation pump and related main filter unit for filtering the pool water. The filtration system is typically operated for several hours on a daily basis to draw water from the pool for flow through the main filter unit and subsequent return circulation to the pool, wherein the filter unit includes an appropriate filter media for collecting and thus removing solid debris such as fine grit and silt, twigs, leaves, insects, and other particulate matter suspended within the pool water. Although such filtration systems function efficiently to collect suspended particulate, it has been recognized that some particulate tends to settle onto submerged pool floor and wall surfaces and thus is not removed by the standard filtration system. Automatic swimming pool cleaners have been developed and are widely used to assist in a more thorough cleaning of the pool by directly collecting such settled matter, and/or by re-suspending the settled matter so that it can be collected by the main filter unit.
More specifically, in one common form, the automatic swimming pool cleaner comprises a relatively compact wheeled housing adapted to travel randomly over submerged floor and wall surfaces of the pool. The cleaner is normally connected by a water supply hose or the like to the standard filtration system, such as by connection to the positive pressure discharge side of the system as described in U.S. Pat. Nos. 6,665,900; 5,863,425; 4,558,479; 4,589,986; and 3,822,754. The filtration system provides a water flow through the supply hose to the cleaner, wherein this water flow is typically used to create or induce an upwardly directed suction flow through a suction mast for vacuuming grit and debris through the suction mast into a porous filter bag mounted on an upper or downstream end thereof. The water flow through the pool cleaner may also be used to power a hydraulic drive means which causes the cleaner to travel about within the swimming pool.
In general terms, the filter bag is constructed from one or more sheets of the porous filter bag material with marginal edges attached or interconnected by seams to form a hollow bag interior with an open bag mouth adapted for removable connection onto the upper end of the pool cleaner suction mast. In the case of a traditional woven fabric bag material, these marginal seams have been formed typically by sewing. Such fabric-based filter bags beneficially accommodate relatively long-term usage, with periodic removal of the filter bag from the pool cleaner suction mast so that collected debris accumulated therein can be discarded followed by re-mounting of the filter bag onto the pool cleaner for a subsequent cycle of use. However, such re-usable filter bags can become worn and/or frayed over time and thus become unsightly, especially in combination with accumulation of residual debris that may including aged organic matter. Exemplary filter bags of this general type and related techniques for removable mounting onto the pool cleaner suction mast are shown and described in U.S. Pat. Nos. 4,618,420; D288,373; 4,575,423; D294,963; 4,589,986; 5,863,425; D409,341; D468,067; and 6,740,233.
More recently, single-use or disposable filter bags formed from a non-fabric or non-woven porous material has been proposed, wherein the bag material is shaped by marginal seams using a thermoplastic or heat-melt adhesive. See, for example, U.S. Pat. No. 6,241,899. Such disposable filter bags are intended for removal from the pool cleaner suction mast when the bag becomes substantially filled with debris, followed by mounting of a replacement disposable filter bag onto the pool cleaner for a subsequent use cycle. Such disposable filter bags, however, have exhibited inconsistent performance with occasional premature bag failure caused by rupture of the seam-forming adhesive material. It is believed that such bag failures have been attributable at least in part to deterioration of the adhesive material when exposed to sun, water and chemical conditions inherent in a swimming pool environment.
In addition, prevention of air entrapment is one important key to proper filter bag performance. Submerged pool cleaner devices are designed with a predetermined buoyancy or buoyancy characteristic to ensure that they can climb pool wall surfaces and traverse floor surfaces of a swimming pool without lifting or significant tilting relative to the pool surface being cleaned. If a filter bag non-woven material is selected that is too thick, air can become entrapped within the filter bag resulting in increased buoyancy and reduced cleaner performance. Adhesive coated filter bag materials and some non-woven materials with excessive point-bonding area can also contribute to this air entrapment problem due to attenuated air flow or reduced available surface area.
U.S. Ser. No. 10/917,790 discloses an improved disposable filter bag for a pool cleaner, wherein the filter bag is constructed from a porous filter material such as a non-woven spunbond polymer having marginal seams formed by direct welding, in the absence of additional adhesive material. In a preferred configuration, such filter bag further includes an elongated divider seam for subdividing the hollow bag interior into a primary flow chamber for receiving flow of water and water-entrained debris from the pool cleaner, and a secondary collection chamber for trapping and collecting the water-entrained debris, generally as shown and described in U.S. Pat. No. 4,618,420. While such filter bag provides a significant improvement in the art, the elongated divider seam has been found to result in localized weakening of the bag material, thereby decreasing bag resistance to undesirable tearing. In addition, this divider seam has terminated abruptly at an upper end, to result in a stress concentration point that is also susceptible to undesirable tearing.
There exists, therefore, a need for further improvements in and to filter bags for pool cleaners, particularly with respect to an improved disposable filter bag designed for removable mounting onto the upper or downstream end of a pool cleaner suction mast, and for convenient and economical disposal together with particulate debris collected therein when the filter bag reached a substantially filled condition. More particularly, there exists a need for an improved disposable filter bag having a divider seam that is highly resistant to tearing. The present invention fulfills these needs and provides further related advantages.